1. Field of the Invention
This invention generally relates to a resistive device, and in particular to a resistive device with flexible substrate.
2. Description of Prior Art
As technology of electric circuit has a continuous development, the requirement for stability of resistance of a resistive device is increased. Some features such as temperature coefficient of resistance (TCR) of traditional chip type resistive device have been not satisfied for the requirement of high stability so that the application is limited.
As shown in FIG. 1, in order to enhance the heat stability of resistance of a resistive device, there has a conventional resistive device 10 provided. The resistive device 10 has a substrate 11 made of ceramic material, a resistive layer 12 located on a lower surface of the substrate 11, a copper foil layer 13 located on an upper surface of the substrate 11, side electrodes 14 respectively located at two sides of the substrate 11 and a protective layer 15 located on the copper foil layer 13. The operative power of the resistive device 10 can be enhanced by the copper foil layer 13 which has excellent heat dissipation to dissipate the heat generated when the resistive device 10 is operated.
However, as the electric device pursues a trend of miniaturization, the resistive device should follow the trend of miniaturization. The substrate of the above resistive device is made of ceramic which is easy to crack during the manufacturing process due to hardness and brittleness. Therefore, there is a limitation for further miniaturizing the resistive device. Moreover, a conventional adhesive for adhering the substrate 11 and the resistive layer 12 or the copper foil layer 13 may contain glass fiber material to provide a preferable support after curing. However, the glass fiber material has poor flexibility after curing, so that there is another limitation for the application of the resistive device. Also, because glass fiber material has poor heat dissipation and may block the heat transfer from the substrate 11 toward the resistive layer 12 or the copper foil layer 13, the operative power of the resistive device 10 cannot be enhanced.